4270520182019eng22716postprint12019-05-282019-05-28--Archival processes of the water stable isotope signal in East Antarctic ice coresThe oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition.
By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation-condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reiheurn:nbn:de:kobv:517-opus4-4270541866-837210.25932/publishup-42705online registrationThe Cryosphere 12 (2018) 5, S. 1745–1766 DOI: 10.5194/tc-12-1745-2018truetrueCreative Commons - Namensnennung, 4.0 InternationalMathieu CasadoAmaelle LandaisGhislain PicardThomas MünchThomas LaeppleBarbara StenniGiuliano DreossiAlexey EkaykinLaurent ArnaudChristophe GenthonAlexandra TouzeauValerie Masson-DelmotteJean JouzelPostprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe716enguncontrolleddronning maud-landenguncontrolledshallow firn coresenguncontrollednear-surface snowenguncontrolledDome CenguncontrolledKohnen stationenguncontrolledSouth Poleenguncontrolledclimate varibilityenguncontrolledVostok stationenguncontrolleddeuterium contentenguncontrolledGCM analysisGeografie, Reisenopen_accessMathematisch-Naturwissenschaftliche FakultätReferiertOpen AccessCopernicusUniversität Potsdamhttps://publishup.uni-potsdam.de/files/42705/pmnr716.pdf